Hot and compressed gas autogenerator



Dec. 1, 1942. R. PATERAS PESCARA 2,303,794

7 HOT AND COMPRESSED GAS AUTOGENERATOR Filed June 19, 1939 4Sheets-Sheet 1 6 in mu 0 Z i z Inventor.- .Ea/ul J mi/ ama feaaam,

Attorneys Dec. 1, 1942. R. PATERAS PESCARA 2,303,794

HOT AND COMPRESSED GAS AUTOGENEBATOR Filgfl June 19,' 1939 4Sheets-Sheet 2 fiverzior M5 fatfafia ra,

14 Ziorneys Dec. 1, 1942. a PATERAS PESCARA H01 AND COMPRESSEDGASAUTOGEN'ERATOR Filed June 19. 1939 4 Sheets-Sheet 5 Dec. 1, 1942. R.PATERAS PESCARA 2,303,794

HOT AND COMPRESSED GAS AUTOGENERATOR Filed June 19, 1939 4 Sheets-Sheet4 lllll/l!!! vi! I VIII/1111A" Fatented Dec. 1, 1942 no'r AND COMPRESSEDGAS AUTOGENERATQB. I

'Raul Pateras Pescara, Paris, France, assignor of one-tenth to SocieteDEtudes et de Participations Eau, Gaz, Electricite, Energies. A. Geneva,Switzerland, a. society of Switzerland Application June 19, 1939, SerialNo. 279,990- In Germany June 21, 1938.

11 Claims.

The. present invention relates to hot and compressed gasauto-generators, this expression designating machines including at leastone motor element, advantageously of the two-stroke type,

and at least one compressor element driven by said motor element, themechanical work of the motor being absorbed by the compressor elementand the motor element being supercharged and scavenged by at least onepart of the air compressed and fed by said compressor element.

The object of the present invention .is to provide a generator of thistype which is better adapted to meet the requirements of practice thanthose used up to the present time, and in particular which works in asafe and reliable manner when the whole is starting and working underlow load.

According to an essential feature of the present invention, I heat, Whenthe system i starting and working under low load, the air intended tosupport combustion in the motor element, either before or after thecompressor element, the degree of heating being preferably automaticallyregulated as a function of the supercharging pressure of the motorelement and in inverse relation thereto.

According to another feature of the present invention, concerningespecially auto-generators of the type above referred to which work witha constant or substantially constant piston stroke and with an outputpressure variable in accordance with a constant or substantiallyconstant compression ratio by means of a preliminary expansion of thefeed air of the compressor element from the pressure of the surroundingatmosphere to the variable feed pressure of this last mentioned element,this preliminary expansion is effected by means of a member adapted toreceive energy, such as a turbine capable of transforming,advantageously in an isothermic manner; at least a portion of the energyreleased by said expansion into work.

According to still another feature of the present invention, whichrelates also to the case of auto-generators having a constant orsubstantially constant stroke of the piston and a pressure variable witha ratio of compression substantially constant by means of the variationof the feed pressure of the compressor element, I provide before thesuction of said compressor element, a pre-chamber in which the pressureis kept substantially constant between two successive suction strokes.

According to still another feature of the present invention, relating toauto-generators of the type above referred to in which the return strokeis ensured by an additional source of energy, I vary the energy of saidsource as a function of the temperature of the combustion supportingair.

Other features of the present invention will result from the followingdetailed description of some specific embodiments thereof.

stantially so, this ratio of pressures depends es-' sentially upon theoutput pressure of said gen-- Preferred embodiments of the presentinvention will be hereinafter described, with reference to theaccompanying drawing, given merely by way of example and in which:

Fig. 1 is a diagrammatic sectional view of a plant including acompressed gas generator having, a given stroke, with pre-heating of thefeed air, according to the invention;

Fig. 2 diagrammatically shows, in section a compressed gas generatorwith free pistons, also fitted with means for pre-heating the feed airprior to its ingress into the motor cylinder;

Fig. 3 is a detail view of the auto-generator according to Fig. 2;

Fig. 4 is a diagrammatical view of a plant including a compressed gasgenerator with free pistons, of the variable suction type, madeaccording to the present invention; y

Fig. 5 is a sectional view of a modification of the device for adjustingthe feed pressure of the compressor element which is a part of theautogenerator of Fig. 4;

Fig. 6 is a diagrammatic sectional View of a compressed gasgenerator'with free pistons, including means for accumulating the energyfor returning the pistons back into initial position,

. this energy being variable in an automatic manner as a function of thetemperature of the air for supercharging the motor element.

In Fig. l, I have shown a hot and*compressed gas auto-generator thepistons of which have a stroke of invariable length. I

In such an auto-generator, the ignition ofthe fuel introduced into themotor element of said generator depends essentially upon the ratio ofcompression existing between the feed pressure of the compressorelement, on the one hand, and

the final pressure of the motor element, on the other hand, and alsoupon the thermic state of the machine.

When use is made of an auto-generator in which the piston strokes areconstant or suberator, this last mentioned pressure determining thedischarge pressure of the compressor element and-consequently, the ratioof compresslonbetween the phases of said element, provided that thesuction pressure of said element remains substantially constant. As arule, the ratio of compression existing between the suction pressure ofthe compressor element and the final pressure of the motor compressionensures, under quite satisfactory conditions, the combustion of the fuelintroduced into the engine cylinder when the output pressure of theauto-generator has its normal or its maximum value, and when, inaddition, the machine has reached its normal thermic state.

But the temperature necessary for the ignition and the satisfactorycombustion of the fuel is no longer obtained when the generator isworking under low load or when the output pressure of the auto-generatoris lower than its normal output pressure and chiefly during startingconditions where not only the pressures are low but also the machine iscold.

The generator shown by way of example by Fig. 1 includes a motor pistonI, working in a motor cylinder 2, having a fuel injection nozzle 2 and acompressor piston 3, working in a compressor cylinder 4, the two pistonsl and 3 being coupled with'a crank-shaft 5. The motor cylinder 2 isscavenged and fed with compressed air from the compressor cylinder 4.For this purpose, the motor and compressor cylinders are fitted withdistribution means consisting, respectively, concerning motor cylinder2, of an inlet valve 6 and exhaust ports I, uncovered near the end ofthe motive stroke by piston l and, concerning compressor cylinder 4, ofinlet valve 8 and ex haust valve 9.

According to the present invention, the suction conduit ID of thecompressor element is placed in communication with a chamber H in whichfuel introduced through burners l2 can be burned.

Preferably, the amount of fuel burned in preheating chamber II is causedto depend upon the one of the working pressuresof the generator, forinstance the exhaust pressure of the motor cylinder 2. In order toobtain this adjustment,

- it is possible, as shown by the drawing, to couple,

with a piston 13 on which said output pressure is caused to act, theadjustment member, such a slide-valve H which permits, according to itsposition, therefore according to the pressure existing in the conduit 1'throught which the motive gases are fed, of feeding a variable number ofburners.

When starting the system, when the supercharge pressure is minimum andwhen the machine is cold, the maximum pre-heating of the air that issucked in is ensured so as thus to obtain, at the end of the compressionstroke of piston l, a temperature such that the combustion supportingair introduced together with the fuel, for instance by means of aninjector, is quickly and fully burned. As the output pressure of theauto-generator increases, the number of burnersin service decreases andwhen the machine is working with full load it can suck in atmosphericair without any preheating.

In the device illustrated by Fig. 1, I have provided still other meansfor obtaining the preheating of the air sucked in by the compressor whenthe generator, after having been started, works under a load lower thanthe normal load. These last mentioned means can act simultaneously withsaid burners, or they maybe substituted for saidburners once thestarting of the machine is obtained.

These last mentioned means mix with the aaosnu pressures of the machine,such as a piston II on which the discharge pressure of the generatoracts in such manner that, when the pressure increases, the ratio of the'weight of exhaust gas in the sucked in air decreases.

It is thus possible, by varying the preheating effect in accordance withthe discharge pressure of the generator, to ensure its operation for allworking pressures and in particular during the starting period.

According to an advantageous embodiment of the invention, it is, forinstance, possible, to dimension the clearance space of the motorcylinder with comparison with the volume thereof in such manner that,for a supercharging pressure corresponding to the maximum load, forinstance for a supercharging pressure of 4 kilograms per squarecentimeter, the final motor-compression pressure is that whichcorresponds with the best possible efiiciency. This final pressurebeing, for instance 55 kilograms per square centimeter. Now, when theload is low (for instance with a supercharging pressure of 1.5 kilogramper square centimeter) the final compression pressure is only 27kilograms per square centimeter, but a preheating of the sucked in airof permits of reaching, at the end of the motor compression, atemperature of 550 0., sufilcient for ensuring ignition of the fuel.

In the example of Fig. 1, the air is preheated before passing throughthe compressor cylinder, but in many cases it is preferable to heat thisair after it has passed through the compressor cylinder and such anarrangement is shown by Fig. 4. In this case, the burners I! arearranged in the wall of the intermediate reservoir 29. In thisarrangement, said burners are controlled in an automatic manner, as afunction of the output pressure of the auto-generator.

The means for pre-heating the combustion supporting air, shown by Fig.1, can also be applied to the case of generators having free pistons,the lower end of the stroke of which is either fixed or variable. In thefirst case, it is as well the reduction of the ratio of the suctionpressure (supposed to be substantially constant) of the compressorelement, on the one hand, and the final pressure of the motorcompression, on the other hand, as the cold state of the machine at thetime of its starting, which necessitate the preheating of the combustionsupporting air, whereas, in the second case (lower end of the strokevariable as a function of the discharge pressure) it is only the coldstate of the machine during the starting period which constitutes thereason for the pre-heating of the combustion supporting air. It istherefore necessary differently to adjust, in these two casesrespectively, the amount of heat introduced into the combustionsupporting air.

Figs. 2 and 3 show an embodiment of the invention which has all theadvantages above indicated and also other advantages which will behereinafter more fully set forth.

It is known that, in existing auto-generators, the ratio of the weightof the fuel and of the weight of combustion supporting air increaseswhen the load decreases due to the considerable asoavae excess ofscavenging air to be compressed for low values or the load. Likewise,the considerable excess 01 scavenging air decreases, in a manner whichis sometimes very disturbing, the temperature of the motor gasesescaping from the motor cylinder.

These drawbacks of known generators, which therefore involve a lowefliciency, are avoided by making use of a generator as shown by Figs. 2and 3.

In this arrangement, I withdraw, at low values of the load, a portion ofthe gases produced by the motor cylinder of the generator for mixing itwith the scavenging air of said motor cylinder.

This is why I provide, for instance, in the wall of motor cylinder I9,provided with inlet apertures and outlet apertures 2|, a suppleber 26connected through conduit 21 (which con- I tains a check valve 28) withthe intermediate reservoir 29 of the auto-generator. This reservoir 29is fed through the compressor element of the generator, which element isconstituted, in

the embodiment shown by Figs. 2 and 3, by a compressor cylinder 30fitted with inlet and discharge valves SI, 32, respectively, and by acompressor piston 33, which is 'also a part or the free piston of themachine.

The pre-heating of the combustion supporting air which is present inreservoir 29 by means of motor gases withdrawn from the motor cylinderhas for its eflect that the temperature-necessary for the ignition ofthe fuel fed into'the motor cylinder, is already reached owing to thefact that the return stroke is shorter, for the motor piston,

than when there is no pre-heating of the com-,

- bustion supporting air. Owing to this shortening of the return strokeof the free piston, I obtain a reduction of the amount of air' sucked ininto the compressor cylinder, therefore a reduction of the compressionwork to be performed in the compressor cylinder, and, consequently, animprove ment of the power per unit of mass of the generator and a riseof the temperature of the motor gas escaping through conduit 34.Furthermore, the fact that I mix with the combustion supporting air acertain amount of combustion gas -improves the conditions of combustionin the motor cylinder. I

The step of withdrawing, as above described, a portion of thecombustion-gases is applicable as well to machines having avariablepiston stroke as to machines having a fixed piston stroke.

Fig. 4 shows an auto-generator of the .free

piston type in which means are provided for varying. during the startingperiod andfor low values of the load of the machine, the feed pressureof the compressor cylinder, whereby the ratio of said feed pressure onthe one hand and the final pressure of compression in the motor, on theother which occurs when the machine has not yet reached these normalthermic conditions, and especially during the starting period.

According to the invention, cooling or the combustion supporting air canbe avoided either by pre-heatin'g the combustion supporting air by meansoi burners it, arranged as above explained on intermediate reservoir 28,and controlled by rod sliding in conduit 3! and connected to piston 62acted on through pipe 63 by the outlet pressure in pipe 3d. Cooling ofthe combustion supporting air can also be avoided by circulating, in thewater jacket ll of the motor cylinder and/or in the water jacket 13 ofthe compressor cylinder, a hot fluid, such as hot water. This water maybe heated in reservoir 73 connected in the cooling circuit by burners80. Pump 10 through conduit H reeds this hot water through reservoir i9and the cooling system; namely, through pipe 32 to jacket 13 with returnthrough pipe 76 to the pump it and reservoir 13; and by A branch pipe F6to jacket ll with return. through pipe 18 to pipe 15. v

I may also preheat the feed air by causing it to circulate in a heatedpre-chamber 36, the heating of said chamber being obtained for instanceby means of a jacket 67 through which circulates a hot fluid, which maybe constituted by at least a portion or the exhaust gases. For example,an.

outlet 34 may feed a turbine 64 having exhaust outlet 65. Part of theexhaust gas from outlet 65 passes through pipe 66 controlled by valve,to Jacket 67 of chamber, and heats the airin the chamber dischargingthrough pipe 63.

In the case of machines as shown by Fig. 4,

' the condition of maintaining the compression ratio in the compressorand in the motor at aconstant value makes it necessary, when workingwith reduced loads, to feed the compressor in depression. that is to saywith a feed pressure lower than atmospheric pressure; For this purpose,the

compressor is fed, not directly from the atmoshand, remainssubstantially constant. In such a machine, the pre-heating oi thecombustion supporting air according to the invention is exclusivelyintended to compensate forthe loss of heat, especially through the wallsof the machine,

phere, but from vessels 35 in which there is a certain, degree ofvacuum. I

This method of regulation by variation oi. the

feed pressure generally involves a considerable re-' duction of theefiiciency, especially when working with small loads, which reduction ofefliciency is chiefly due to the fact that the preliminary wiredrawingof the feed air absorbs avconsiderable amount of work. a

According to the invention, at least a portion 'of this work isrecovered by transforming into mechanical energy at least a'portion ofthe energy brought into play by the preliminary drop of I pressure.

For this urpose. I inter ose, before the suc an adiabatic line (iffinthis case, care is taken to compensate for the correlative drop of thetemperature by a heating of the feed air) or accords preheating then ataking place in the turbine itsel r ing to an isothermic line, the

During the starting peno chamber as is t5 be brought to a pressure lowerthan atmospheric pressure, for instance by means 01' a'vacuum pump '31.When working, the depression in 1 chamber 35 may be regulated by actingon the feed of the turbine, forinstance by means of a valve 33.

In any case, and whatever he the member :em I

ployed for placing chamber 35 under vacuum, the

expansion of the feed air, whether it produces an external work or not,must not lower the temperature substantially below the temperature ofthe surrounding atmosphere, and this whatever be the degree of vacuum.

According to a modification of the generator shown by Fig. 4, I causethe depression or vacuum in pre-chamber to be substantially held betweentwo successive suction strokes of the compressor piston. Thismodification is shown by Fig. 5, in which the element, which producesthe drop of pressure in the sucked in air, is constituted for instanceby a valve 39 with alternating control means such that it opens by thedesired amount only during the time of suction of the compressor element30.

For this purpose, it is possible to control valve 39, as shown by Fig.5, through the very pressure existing in chamber 35 for instance, asshown, by means of a deformable box 40, subjected, in addition to theopposing actions of the external pressure and of the pressure of chamber35, to the action of a spring 4| the tension of which is adjustable, forinstance by means of a cam 42. This cam 42 is actuated by means of alever 43, controlled for example automatically by the governor of theturbine, so as thus to vary the pressure in chamber 35. As shown,turbine 64 drives a shaft on which is mounted a governor 84, whichthrough bell crank lever 85, rod 83, bell crank lever 82 and rod 8|turns lever 43 rigid on shaft 43 of cams 42. Valve 39 is connected tobox by means of a rod 44. Advantageously, I further provide lockingmeans 45 varied by a hinge pivot 46 and adapted to permit of locking theregister in its closing position.

The device shown by Fig. 5 works in the following manner:

Valve 39 remains closed as long as there exists inside chamber 35 apressure higher than that determined by the position of cam 42. Onlywhen the pressure in chamber 35 drops below the pressure determined bycam 42 does the atmospheric pressure, acting on the bottom of deformablebox 40, produce the opening of valve 39 against the action of spring 41Generally, before starting the machine, I produce, by means of pump 31,on the inside of chamber 35, a suction corresponding to the position ofcam 42. After the starting of the machine, the

suction in the compressor element produces the opening of 'the inletvalves 3i in such manner that the pressure of chamber 35 drops slightlybelow the pressure determined by the position of cam 42. It follows thatvalve 39 opens so as to keep in chamber 35, during the suction, thedesired degree of vacuum. The suction finished, valve 39 closes at leastpartly in such manner that the suction in chamber 35 is practicallymaintained til the next suction stroke takes place. The compressorelement therefore sucks in from a chamber in which there is always apredetermined degree of vacuum, this degree being variable andadjustable by means of cam 42 as a function of the speed, and thereforeof the load of the turbine.

Before starting, while the suction is being created by means of pump 31,valve 39 is kept in the closed position by means of locking device 45.

Finally, Fig. 6 shows another modification of the auto-generatorillustrated by Fig. 4. According to this embodiment, instead ofpreheating the combustion supporting air or simultaneously with thispreheating, I act, as a function of at least one of the temperatures ofthe machine, for instance the temperature of the combustion supportingair in intermediate reservoir 29, on the return energy accumulated in apneumatic energy accumulator 41, which maintains a reduced pressure onthe rear face of the piston, thus ensuring the return of free piston 23,33 to its inner stroke end. Supposing, for instance, as shown by saidFig. 6, that the pneumatic energy accumulator 41 is disposed in thecompressor cylinder and limited by the non-active face of the compressorpiston 33, so as to act by suction during the return stroke of thepiston system, it is possible to vary the energy of this cushion and,consequently, the energy which ensures the return of said sys-' tem, asa function of the temperature, by placing chambers 38 and 41 incommunication, for instance through a valve 48 the opening and/or theclosing of which depends upon the temperature existing in reservoir 29.For this purpose, it is, for instance, possible to open valve 48, closeto the inward end of the stroke, by contact against an abutment 49 theposition of which depends upon the temperature of reservoir 23. Forinstance, this abutment 49 is subjected to the action of a sliding cam50 connected with a thermostat 5| arranged in reservoir 29. With such adevice, if the temperature rises, valve 48 is opened earlier and closedlater and, consequently, the energy stored up in accumulator 41decreases.

The communication, opened, for each cycle, at the end of the suctionstroke of the compressor cylinder, between chambers 38 and 41 furtherhas for its effect to render the feed pressure of energy accumulator 41proportional to the variable pressures of the generator.

Anyway, whatever be the particular embodiment that is chosen, I alwaysobtain an auto-generator in which ignition and quick and completecombustion of the fuel are obtained in a reliable manner, as well whenworking with full load as when working with small loads and during thestarting period.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efficient embodiments of the presentinvention, it should be well understood that I do not wish to be limitedthereto as there might be changes made in the arrangement, disposition,and form of the parts without departing from the principle of thepresent invention as comprehended within the scope of the appendedclaims.

What I claim is: g

1. A hot and compressed gas auto generator which comprises, incombination, at least one motor element and at least one compressorelement driven by said motor element each having a variable outputpressure, means for interconnecting said two elements so that themechanical work of the motor element is absorbed by the compressorelement, said motor element having gas outlet-means, means for feedingthrough said motor element to said gas outlet at least a part of the airfed by said compressor element for scavenging and supercharging saidmotor element to support combustion therein, means for preheating thecombustion supporting air fed to said motor element, and meansresponsive to variations in the pressure of gas in the auto-generatorfor controlling said last mentioned means automatically to decrease thepreheating as such pressure increases.

2. A generator according to claim 1 in which said preheating meansinclude at least one means for burning fuel in combustion supporting airon its way toward said compressor element.

3. A generator according to claim 1 in which said preheating meansinclude a plurality of of said motor element is absorbed by said com- 7pressor element, means for feeding through said motor element to saidgas outlet at least a part of the air fed by said compressor element forscavenging and supercharging said motor element to support combustiontherein, means for mixing at least a part of the combustion gases withthe combustion supporting air of the motor element. on its way towardsaid motor element, when starting said generator or operating it with asmall load, and means responsive to variations of the pressure of gas inthe auto-generator for controlling said last mentioned meansautomatically to reduce the amount of combustion gases so mixed as thepressure increases.

5. A system according to claim 4 further including a receiver machineoperated by said generator, the combustion gases introduced into thecombustion supporting air on its way toward said motor element comingfrom said receiver machine.

generator for controlling the amount of fuel supplied to said burners.

8. A generator of the type described, which comprises, in combination,at least one motor element and at least one compressor element driven bysaid motor element each having a variable output pressure, means forinterconnecting said two elements so that the mechanical work of saidmotor element is absorbed by said compressor element, said motor elementhaving gas outlet means, means for feeding through said motor element tosaid gas outlet at least a part of the air fed by said compressorelement for scavenging and sup'ercharging said motor element to supportcombustion therein, means for withdrawing at least a part of thecombustiongases of said motor element and mixing them with thecombustion supporting air under pres- 5 a variable output pressure,means for intercon- 6. In combination, a hot andcompressed gas generatorincluding at least one motor element and at least one compressor elementdriven-by said motor element each having a variable output pressure,means for interconnecting said two elements so that the mechanical workof the motor element is absorbed by the compressor element, said motorelement having gas outlet means,

means for feeding through said motor element 1, receiver machine, andmeans operative by said valve means for simultaneously controlling, inopposed relation a direct communication between the intake conduit ofthe compressor element and the atmosphere.

'l. A generator plant according to claim 6 having means for heating thecombustion supporting 'air fedto motor element including burners mountedacross the path of the exhaust gases, from the receiver machine towardthe intake conduit of said compressor element, and means operative inresponse to the output pressure of said necting said two elements sothat the mechanical work of the motor element is absorbed by thecompressor element, said motor element having gas outlet means, meansfor feeding through said motor element to said gas outlet at least apart of the air fed by said compressor element for scavenging andsupercharging said motor element to support combustion therein, energyreceiving means for subjecting the air sucked in by said compressorelement to a preliminary expansion and means responsive to variations inthe output, pressure to control said means to vary the degree of suchexpansion upon variations in the output pressure.

10. A hot and compressed gas auto-generator which comprises, incombination, at least one motor element and at least one compressorelement driven by said motor element each having a variable outputpressure, means for interconnecting said two elements so that themechanical work of the motor element is absorbed by the compressorelement, said motor element having gas outlet means, means for feedingthrough said motor element to said gas outlet at least a part of the airfed by said compressor element for scavenging and supercharging saidmotor element to support combustion therein, means for subjecting theair sucked in by said compressor element to a preliminary expansion, anda prechamber interposed between said expansion means and said-compressorelement adapted to keep the expansion pressure at a substantiallyconstant value. Y

11. A generator according to claim 10 further including an auxiliarypump connected with said prechamber for producing a given suctiontherein before the starting oLthe machine.

RAUL PATERAS PESCARA.

